Who Owns Mercer?

William Manson Mercer founded William M. Mercer Limited in Vancouver in 1945 as an actuarial and employee benefits consulting firm. The postwar expansion of employer pension plans created growing demand for exactly this expertise, and the firm grew steadily across Canada.

Marsh & McLennan acquired the firm in 1959 and expanded it into the United States and international markets. Through the 1970s, the parent consolidated its employee benefits and actuarial operations into William M. Mercer, Inc. The acquisition of additional consultancies followed: National Economic Research Associates in 1983, Lippincott and Margulies in 1986, Temple, Barker & Sloane in 1987, and Strategic Planning Associates in 1989.

In 1992, Marsh & McLennan formed the Mercer Consulting Group to house its expanding consulting operations. The structure separated human resources consulting, kept under the Mercer name, from strategy and management consulting, which became Mercer Management Consulting, and organizational consulting, known as Mercer Delta.

The 2003 acquisition of Oliver, Wyman & Company triggered another reorganization. Mercer Management Consulting merged with Oliver Wyman and Mercer Delta to form Mercer Oliver Wyman. In 2007, the strategy consulting units were unified under the Oliver Wyman brand, while the human resources consulting business continued simply as Mercer. NERA and Lippincott moved to the Oliver Wyman Group.

Modern Mercer operates across three principal areas: Health, covering employee benefits and healthcare cost strategy; Wealth, covering retirement, investment consulting, and delegated investment management; and Career, covering workforce strategy, compensation data, and HR transformation. Its delegated investment management business, often called OCIO or fiduciary management, administers hundreds of billions of dollars in client assets globally.

In October 2025, the parent announced that Mercer will adopt the Marsh masterbrand beginning in 2027, going to market under the Marsh name while continuing to serve its consulting clients.